Age-specific and menopause-specific associations between BMI change and the risk of cervical and ovarian cancers: a population-based cohort study

OBJECTIVES: The association between longitudinal body mass index (BMI) change and the risk of cervical and ovarian cancers remains uncertain. We assessed those associations, evaluating modification by age and menopausal status. METHODS: We conducted a population-based cohort study of 1.464 million women who completed national health examinations in 2009 and 2013 and were followed through 2017. BMI was categorized using the Asia-Pacific criteria, and 2009-2013 BMI changes were classified into 25 groups. RESULTS: During 12,661,743 person-years, 975 cervical and 1,570 ovarian cancers occurred. Excessive BMI gain from normal to obesity I was associated with increased cervical cancer risk (adjusted hazard ratio [aHR], 3.41; 95% CI: 1.73-6.72), particularly among postmenopausal women. BMI gain from underweight to normal was linked to elevated ovarian cancer risk. BMI change showed heterogeneous associations with ovarian cancer risk, with associations differing by age group. Persistent overweight (aHR: 0.79; 95% CI: 0.65-0.95) and obesity I (aHR: 0.68; 95% CI: 0.57-0.81) was associated with reduced ovarian cancer risk in women below 60 years, whereas BMI gain from normal to obesity I (aHR: 3.23; 95% CI: 1.30-8.04), persistent overweight (aHR: 1.60; 95% CI: 1.14-2.30) and obesity I (aHR: 1.45; 95% CI: 1.05-2.00) were associated with increased risk in those ≥60 years. CONCLUSIONS: BMI change was associated with cervical and ovarian cancer risk, with direction and magnitude varying by age.